EFFECTS OF LIGHT INTENSITY ON GROWTH AND PRODUCTIVITY OF TAM THAT (Panax pseudoginseng Wall) IN MUONG KHUONG AND SI MA CAI DISTRICT, LAO CAI PROVINCE

Abstract

This study was conducted to evaluate the effects of light shading using polyethylene (P.E) net cover on the survival rate, average height, SPAD, disease incidence on leaves and root productivity of Panax pseudoginseng Wall. The P. pseudoginseng Wall grown under the P.E net shading at 65% and 75% light intensity showed a significant increase in the survival rate but a significant decrease in the survival rate at 50% and 85% light intensity. The formula of 75% shading the height of the stem also reached the highest value. In the second year, the height in Muong Khuong district was 33.8 cm while Si Ma Cai district was 32.5 cm. In the third year, the height of the tree in Muong Khuong district was 51.2 cm, the stem height in Si Ma Cai district was 50.3 cm. The SPAD index reached the highest value at 75% light intensity, at 50% and 85% light intensity, the SPAD index was the lowest. The lowest disease incidence on leaves in the formula of 65% light intensity, In Muong Khuong district this rate was 6.8 - 9% in the second year and was 5 - 7.6% in the third year while in Si Ma Cai district, this rate of the second year was from 5.8 to 8.5% and was from 4.6 -7.1% in the third year. The P. pseudoginseng Wall grown under the P.E net shading at 65% and 75% light intensity showed the highest root weight. The average root weight in Muong Khuong district reached 26.08-26.24 g, The average root weight in Si Ma Cai district reached 24.88 - 25.54g in the 3rd year.